The Uncanny Valley is a theory first proposed by Masahiro Mori that posits that people find a robot more familiar, the more human-like its appearance is, but there is a sharp drop, once the robot looks very realistic but not quite real, where our reaction turns to disgust, before rising again once we can no longer distinguish it from a real human. Mori expected the effect to be more pronounced for moving robots as opposed to still images.

The Uncanny Valley is a theory first proposed by Masahiro Mori that posits that people find a robot more familiar, the more human-like its appearance is, but there is a sharp drop, once the robot looks very realistic but not quite real, where our reaction turns to disgust, before rising again once we can no longer distinguish it from a real human. Mori expected the effect to be more pronounced for moving robots as opposed to still images.

Mori's graph of the Uncanny Valley